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-rw-r--r--block/qcow2-refcount.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index aa3fd6cf17..9059996c4b 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -367,6 +367,13 @@ static int alloc_refcount_block(BlockDriverState *bs,
return new_block;
}
+ /* If we're allocating the block at offset 0 then something is wrong */
+ if (new_block == 0) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid "
+ "allocation of refcount block at offset 0");
+ return -EIO;
+ }
+
#ifdef DEBUG_ALLOC2
fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
" at %" PRIx64 "\n",